[morelisp]

The manager is such a blank slate in this story it's almost useless to discuss, but what stood out for me was:

"A manager came to me asking if we should rewrite the checkout of our E-Commerce platform using React... in order to make an informed decision, I needed to understand a few things: ... Why do they think a technology change is a solution? Do they understand the implications of such a switch?"

What problems such a switch might solve and what the implications are is what the manager is asking you. Why would you direct exactly those questions back to them?